Casarotto S, Bianchi A M, Ricciardi E, Gentili C, Vanello N, Guazzelli M, Pietrini P, Chiarenza G A, Cerutti S
Laboratory of Clinical Biochemistry and Molecular Biology, Department of Experimental Pathology, Medical Biotechnologies, Infectivology, and Epidemiology, University of Pisa, Pisa, Italy.
Arch Ital Biol. 2008 Jun;146(2):83-105.
This work investigates the neural correlates of single-letter reading by combining event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), thus exploiting their complementary spatiotemporal resolutions. Three externally-paced reading tasks were administered with an event-related design: passive observation of letters and symbols and active reading aloud of letters. ERP and fMRI data were separately recorded from 8 healthy adults during the same experimental conditions. Due to the presence of artifacts in the EEG signals, two subjects were discarded from further analysis. Independent Component Analysis was applied to ERPs, after dimensionality reduction by Principal Component Analysis: some independent components were clearly related to specific reading functions and the associated current density distributions in the brain were estimated with Low Resolution Electromagnetic Tomography Analysis method (LORETA). The impulse hemodynamic response function was modeled as a linear combination of linear B-spline functions and fMRI statistical analysis was performed by multiple linear regression. fMRI and LORETA maps were superimposed in order to identify the overlapping activations and the activated regions specifically revealed by each modality. The results showed the existence of neuronal networks functionally specific for letter processing and for explicit verbal-motor articulation, including the temporo-parietal and frontal regions. Overlap between fMRI and LORETA results was observed in the inferior temporal-middle occipital gyrus, suggesting that this area has a crucial and multifunctional role for linguistic and reading processes, likely because its spatial location and strong interconnection with the main visual and auditory sensory systems may have favored its specialization in grapheme-phoneme matching.
这项研究通过结合事件相关电位（ERP）和功能磁共振成像（fMRI）来探究单字母阅读的神经关联，从而利用它们互补的时空分辨率。采用事件相关设计进行了三项外部节奏阅读任务：对字母和符号的被动观察以及对字母的出声朗读。在相同实验条件下，从8名健康成年人中分别记录ERP和fMRI数据。由于脑电图信号中存在伪迹，两名受试者被排除在进一步分析之外。在通过主成分分析进行降维后，对ERP应用独立成分分析：一些独立成分与特定阅读功能明显相关，并使用低分辨率电磁断层扫描分析方法（LORETA）估计大脑中相关的电流密度分布。将脉冲血流动力学响应函数建模为线性B样条函数的线性组合，并通过多元线性回归进行fMRI统计分析。将fMRI和LORETA图谱叠加，以识别重叠激活区域以及每种模式特有的激活区域。结果表明，存在专门用于字母处理和明确言语运动发音的神经元网络，包括颞顶叶和额叶区域。在颞下回 - 枕中回观察到fMRI和LORETA结果之间的重叠，这表明该区域在语言和阅读过程中具有关键的多功能作用，可能是因为其空间位置以及与主要视觉和听觉感觉系统的紧密连接可能有利于其在字形 - 音素匹配方面的特化。
